Several different designs of matrix crosspoint switching devices of the kind defined in the introduction are known to the art and adapted for different applications.
With regard to the constructive design of these switching devices, it may be appropriate to divide the same into different categories.
A first category utilizes a contact device which includes electrically conductive balls placed in selected crosspoints between first and second rods arranged in rows and columns, where electrically conductive balls associated with respective rods can be moved to a position in which the ball (as a movable contact element) is able to make an electric circuit terminating in two fixed contacts, or to a position in which the ball breaks the circuit.
The following publications are recited as examples of prior art disclosures in this regard:
U.S. Pat. No. 4,954,674
This publication describes and illustrates a matrix crosspoint switching device which makes, breaks or switches contacts between a plurality of first conducting pairs and a plurality of second conducting pairs.
The device includes a connection block that has a plurality of cavities (H1) containing crosspoints of the pluralities of conductor pairs, said cavities (H1) accommodating a first ball 1 (electrically conductive) and a second ball 2 (electrically insulating).
The ball (1) rests against two metal tongues (51, 52) which extend into the cavity in the x-direction from a y-conductor (5) moulded in the block (K).
A leaf-spring (61) extends in the z-direction from an x-conductor (6), which as the y-conductor (5) is moulded in the block (K).
The electrically conductive ball (1) makes contact with an outwardly bent tongue (61a) of the leaf spring.
The balls (1-4) are positioned In the cavity (H1) such as to provide electric contact between incoming conductor pairs (9, 6) in the x-direction and outgoing conductor pairs in the y-direction.
U.S. Pat. No. 5,214,400
This publication describes and illustrates a switching device for electrically making or breaking an electric circuit allocated a selected crosspoint from among a plurality of available crosspoints in a three-dimensional switching matrix.
This device includes three different actuator elements, each including a plurality of rods and used to move an electric contact element placed in the proximity of a selected crosspoint.
The contact elements have the form of balls, one electrically conductive and one electrically insulating, so as to enable a crosspoint-related circuit to be made or broken.
A rod (11a ), referred to as an x-rod and including a first actuating element (11) can be moved in the x-direction from a neutral position (broken lines) to an active position.
A contact making element (10), which is placed initially outside the crosspoint but in the proximity thereof in a recess in the rod in one position (1), is moved by the rod (11a) to a new position (2), and a rod (12a), referred to as a y-rod and included in a second actuating element (12), is perpendicularly movable to the rod (11a) in the x-direction.
The rod (12a) is moved from its neutral position to an active position and the contact element (10) is moved to a position (3) and is placed in a recess in a rod (13a), a z-rod, included in a third actuating element (13).
The rod (13a) can be moved in the z-direction perpendicularly to both the x-rod (11a) and the y-rod (12a), and is used as a make/break function during movement of the contact element (10) to and from a chosen position (4).
DE 2 214 686
This publication illustrates and describes a matrix contact device having a ball-shaped contact element.
The electrically conductive ball (6) can be brought to a contact-making position (7) or a contact-breaking position by actuator means (13).
DE-A 867 703
This publication describes and illustrates a switching device which comprises rods that are movable reciprocatingly in the x-direction and y-direction. The rods are provided with grooves which function to move an electrically conductive ball situated in a selected crosspoint towards and away from electric contacts positioned at said crosspoint.
A second category uses contact devices located in selected crosspoints between rods arranged in rows and columns, said contact device including at least one movable contact element in the form of a movable contact spring which can be moved towards and away from a fixed contact by actuator means.
The following publications disclose examples of this second category of such switching devices:
U.S. Pat. No. 3,662,301
This publication discloses a switching system having a plurality of coordinate-related contact setups orientated in rows and columns.
The system includes reciprocatingly movable actuating rods adapted for actuation of a crosspoint-related contact setup.
The contact setup is adapted for plug-in coaction with a panel (16) having circuits (18) formed on boards or panels in a manner typically known in printed circuit board techniques.
U.S. Pat. No. 3,711,670
This publication illustrates a switching system which includes a plurality of coordinate-related contact setups orientated in rows and columns.
Contact setups in the form of contact springs are provided in the crosspoints, and the system includes an actuator means which can be moved by angle-related rods to a contact-spring actuating position or to a contact-spring releasing position.
U.S. Pat. No. 2,647,166 and CH-A5 584 965 are also pertinent publications in the present context.
The present invention can be considered to belong to the category in which crosspoint-related contact devices include a movable contact element in the form of a movable contact spring, and in which movement of the contact spring to an open or a closed state is effected by movement of an electrically insulating ball.